The present invention relates to a fluid machinery of a helical structure adapted to continuously deliver a fluid to be compressed in an axial direction thereof, and more particularly, relates to a fluid machinery provided with an air cooling system.
An indoor type air conditioner, a refrigerator, a freezing chamber such as freezing showcase or like is assembled with a freezing cycle or freezing system, and such freezing cycle is incorporated with a compressor for compressing a refrigerant or cooling medium. Such compressor includes a reciprocal type one or rotary type one, but in recent years, a helical type compressor utilizing a helical blade for a compressing mechanism has been developed.
One example including such helical type compressing mechanism is disclosed in Japanese Patent Laid-open (KOKAI) Publication HEI 11-132176, in which a lubricating oil for lubricating a sliding portion of the compressing mechanism is generally utilized for cooing a machinery chamber, motor or like.
However, for the purpose of using a freezing cycle utilizing the helical mechanism, it is not always desired to use the lubricating oil, and such requirement is not satisfied by the helical compressor disclosed in the above prior art publication. Hence, it has been desired to provide a fluid machinery having a compact structure capable of cooling the helical mechanism without utilizing any lubricating oil.
An object of the present invention is therefore to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a fluid machinery, which comprises:
a helical mechanism provided with a cylinder, a roller eccentrically disposed inside the cylinder and formed with a helical groove and a blade member fitted in the helical groove;
an electric motor unit operatively connected to the helical mechanism through a rotational shaft so as to drive the helical mechanism, said roller, which eccentrically rotates, having an engagement portion engaged with a crank portion of the rotational shaft; and
a pair of bearings disposed to both axial end portions of the cylinder so as to support the rotational shaft, the engagement portion of the roller and the bearings being formed with through holes for ventilation, respectively.
According to the fluid machinery of this aspect, the helical mechanism and the electric motor unit can be cooled by the air without utilizing lubricating oil or like cooling medium. Furthermore, the rotational shaft has a small eccentricity in comparison with the rotational shaft of a conventional reciprocal compressor, rotary compressor or like, so that the cylinder or like member can be made compact, thus providing a compact fluid machinery.
In preferred embodiments or examples of the above aspect, the fluid machinery further comprises a fan mounted to an axial end portion of the rotational shaft. The fan may be disposed on the side of the helical mechanism or on the side of the electric motor unit.
The cylinder is formed of an aluminium including material such as aluminium alloy.
The cylinder is provided, at an outer periphery thereof, with fins for heat radiation.
The helical groove has a pitch gradually reduced along an axial direction of the roller.
The helical groove has a pitch substantially equal along an axial direction of the roller.
The cylinder has an outer periphery to which fluid suction port and fluid exhaust port are formed for the fluid to be delivered by the helical mechanism.
The fluid machinery may further comprises a cylindrical case into which the helical mechanism and the electric motor unit are accommodated, the cylindrical case being provided with openings for ventilation formed to both axial end portions thereof.
The cylinder has an outer periphery secured to an inner periphery of the case so as to define a ventilation space therebetween. The outer periphery of the cylinder has a cross section of the shape substantially the same along an axial direction thereof.
According to such preferred embodiments, the location of the fan at the end portion of the rotational shaft allow the helical mechanism and the motor unit to be effectively cooled by air and to be aligned with the shaft, making possible to provide a compact structure of the fluid machinery.
Since the cylinder is formed from an aluminium including material, the heat radiation from the cylinder can be enhanced. This heat radiation will be further enhanced through the fins formed to the outer periphery of the cylinder.
Since the engagement portion of the roller of the helical mechanism and the main and counter bearings mounted on the rotational shaft to support the same are provided with the through holes for ventilation, the bearing, the roller and the helical blade of the helical mechanism can be effectively cooled.
Furthermore, in a case where the helical groove is formed to have a pitch gradually reduced along an axial direction of the roller, so that a small sized air-cooling helical compressor may be provided. Further, in a case where the helical groove has a pitch substantially equal along an axial direction of the roller, a small sized air-cooling helical pump may be provided.
Still furthermore, the fluid machinery may further comprises a cylindrical case into which the helical mechanism and the electric motor unit are accommodated with a space or gap therebetween, and the cylindrical case being is provided with openings for ventilation formed to both axial end portions thereof. In this example, the cylinder can be cooled more effectively.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.